Sound suppressors for firearms have been used for over a century to reduce the sound of muzzle blasts from firearms by impeding the rapid release of gases produced by ignited bullet propellant. Sound suppressors often have a plurality of baffles which are directly connected to one or more gas expansion chambers. The gas expansion chambers may be integral with or part of baffle components. Some firearms have integrated sound suppressors in which the barrel has multiple ports extending down the length of the barrel which are connected to one or more expansion chambers.
Prior art sound suppressors have also included wipers formed of soft materials which are mounted to extend across the bore of a suppressor and either have perforations which conform closely to the gauge of the round being fired or which are perforated by the first round being fired through a suppressor. Wipers provide a gas check feature to assure that propellant gases do not exit a firearm suppressor prior to the projectile exiting the suppressor. These type of wipers were lower cost and did not require precision machining. Wipers formed of soft material will typically have to be replaced after a few rounds are fired.